Silage fermentation characteristics and bacterial community diversity of sorghum–sudangrass hybrids: A case study on variety selection in Hulunbuir region

Abstract

Selecting high‐quality forage cultivars is essential for stabilizing regional forage supply and enhancing feed conversion efficiency. To identify suitable varieties for the Hulunbuir region, this study evaluated five sorghum–sudangrass hybrids (designated SS1–SS5). The evaluation was conducted by comprehensively analyzing their agronomic traits, silage quality and bacterial community diversity. Forage materials were harvested at the late milk stage. After being chopped and vacuum‐sealed, the samples were subjected to 60‐day fermentation. Among the tested hybrids, SS4 exhibited superior comprehensive performance. It achieved the highest ( P  < .05) fresh forage yield (8.48 t/hm ² ) and the largest ( P  < .05) stem diameter (22.00 mm). In terms of silage fermentation quality, SS4 also outperformed its counterparts. It was characterized by the highest ( P  < .05) lactic acid concentration (26.30 g/kg DM), which was markedly higher ( P  < .05) than the range of 14.20–19.50 g/kg DM observed in other hybrids. Concurrently, SS4 had the lower ( P  < .05) pH value (3.67 vs. 3.73–3.95). It also showed lower neutral detergent fiber content (540 g/kg DM vs. 603–640 g/kg DM) and acid detergent fiber content (317 g/kg DM vs. 388–430 g/kg DM). Microbiological analysis showed that ensiling shifted bacterial dominance from Proteobacteria to Firmicutes. Specifically, SS4 selectively enriched Lactobacillu s (58.2%) and Nitrospira (2.5%). The Kyoto Encyclopedia of Genes and Genomes (KEGG) functional prediction further indicated that this bacterial community succession substantially upregulated carbohydrate and energy metabolism pathways. Furthermore, SS4 presented a robust fibrolytic potential, as evidenced by the enhanced ( P  < .05) expression of cellulase (EC 3.2.1.4) and endo‐1,4‐ β ‐xylanase (EC 3.2.1.8). In conclusion, SS4 is the optimal candidate for promotion as the primary forage variety in the Hulunbuir region.